Telephone system



May 19; 1936.

o. MYERS TELEPHONE SYSTEM Filed Dec. 29, 1934 4Sheets-Sheet l lNl/ENTOR OMVERS ATTORNEY TELEPHONE SYS TEM Filed Dec. 29, 19:54 4 Sheets-Sheet 2 & I l' U STAT/0N5 5 THOUSANDS U HUNDREDS U rnvs n m'nu no u u m n A TTORNE V May 19, 1936. o. MYERS r 1 2,041,084

' TELEPHONE SYSTEM Filed Dec. 29, 1934 4 Sheets-Sheet s POSITION cmcu/r h, E 1 g INVENTOR y OMVERS ATTORNEY May19, 1936. I o. MYERS 2,041,084

- TELEPHONE SYSTEM Filed Dec. 29, 1954 4 Sheets-Sheet 4 POSITION 30/ CIRCUIT By aMrERs A T TORNE V Patented May 19, 1936 TELEPHONE SYSTEM Oscar Myers, Brooklyn, N. Y., assignor to Bell Telephone Laboratories, YorlnN. Y., a corporation of New York Incorporated, New

Application December 29, 1934, Serial No. 759,666

9 Claims.

This invention relates to a telephone exchange system and more particularly to circuits for enabling the registration of the digits of a called line number in the registering mechanism of a manual office or at a tandem office by means of series'of code impulses transmitted from the sender of an originating office.

Heretofore circuits of this character as disclosed, for example, in Patent No. 1,968,420

- granted July 31, 1934 to A. C. Powell, have employed three impulse responsive relays connected in a bridge across the conductors of the cable loop extending from the sender of the originating office to the digit registering equipment of the terminating manual ofiice. Two of these relays are polarized, one responsive to impulses of negative polarity only and the other responsive to impulses of positive polarity only. The third relay is responsive to impulses of either polarity, but is so margined as to respond only to impulses of increased current strength. The three relays cooperate to sequentially select relay registers and to control the selective operation of the relays of each register. The registers after they have assumed their settings are then instrumental in selectively lighting lamps on a display board to display the number of the subscribers line terminating in the manual ofiice which the calling subscriber has dialed and caused to be transferred to the manual oflice by series of code impulses transmitted by the sender of the originating office.

Accurate response to the series of code impulses transmitted over the control conductors is dependent to a great degree on the design and adjustment of the three impulse responsive relays associated with the control circuit and this'is particularly true of the marginal relay which is dependent upon the restriction of the resistance of the control circuit within certain definite limits. It is therefore the object of the present invention to increase the accuracy of the registration of wanted line numbers in the display equipment of an operators position, or the. registration of E line numbers in the registering equipment of a tandem sender in response to series of code impulses transmitted thereto from an originating office; to make possible the transmission of impulses over longer control circuit loops: to eliminate the effect'of leakage and capacity of the conductors of the control circuit; to enable response to impulses of shorter duration and toeliminate the use of polarized and marginal impulse responsive relays.

In accordance with the present invention, use

is made ofgaseous conductor tubes as impulse responsive relays. The gaseous conductor tube employed is a tube filled with a low pressure gaseous content which, for purposes of illustration, might be neon, argon, helium, mercury vapor or combinations of gases of this group. The tube has a certain characteristic, namely, that the gaseous content will become ionized and thus conducting on one potential .determined by the electrode design, the nature of the gaseous content and its pressure. As disclosed, each tube is of the hot cathode type having a filament heated by either direct or alternating current and a cathode heated conductively from the filament. Obviously, a hot cathode type of tube in which the filament, heated by direct current, serves as the cathode or a cold cathode type of tube might be employed. Each tube functions as an ionic relay to establish an operating circuit for an impulse responsive relay included in the cathodeanode circuit thereof. The relay associated with each tube may be of simple, efiicient design since it is not required to be selective to current margins or reversal of potential over the control circuit extending from the sender of the originating ofiice;

For the purpose of illustration, the invention has been disclosed in connection with the registering equipment of a manual ofilce essentially similar to that disclosed in the patent to Powell previously referred to.

In order to simplifythe disclosure, only one of the .digit registers and. associated display lamps has been illustrated and the operators position equipment, by means of which an incoming call is answered and completed to a wanted line as indicated by the number displayed, has been omitted and designated by a rectangle labeled position circuit. For transmitting code impulses to the registering equipment of the manual oflice only so much of the sender of an originating oflice has been disclosed as is necessary for connected through the windings of associated impulse responsive relays to the ring conductor and their cathodes connected to the tip conductor. The grids of these two tubes may be negatively biased with diirerent potentials to provide definite breakdown potentials for the tubes, or the tubes may be selected for inherent breakdown potential and operate without grids. One of these tubes breaks down when a low potential negative impulse is applied to the tip conductor and ground is applied to the ring conductor and thus oper-.

ates the impulse responsive relay over its cathode-anode circuit andboth tubes break down when a high potential negative impulse is applied to the tip conductor and ground is applied to the ring conductor and thus operate the two impulse responsive relays associated with their cathodeanode circuits. The other. two tubes have their anodes connected through the windings of associated impulse responsive relays to the tip conductor and their cathodes connected to the ring conductor. The grids of these tubes may be negatively biased to different potentials to provide definite breakdown potentials for these tubes, or the tubes may be selected for inherent breakdown potential and operate without grids. One of these latter tubes breaks down when a low potential positive impulse is applied to the ring conductor and ground is applied to the tip conductor and thus operates the associated impulse responsive relay over its cathode-anode circuit and both of these tubes break down when a high potential positive impulse is applied to the ring conductor and ground is applied to the tip conductor and thus operate the two impulse responsive relays associated with their cathode-anode circuits. All relays release upon the deionization of the tubes following the removal of battery potential on the cathodes or ground from the anodes and since each relay is in series with a tube it releases in an open circuit. The polarized and marginal effects are obtained from the tubes and therefore all relays are alike and non-polarized. A gain in the length of impulse necessary results from the use of more sensitive tubes as ionic relays and the avoidance of release against the leak and capacity of the control circuit. The impulse responsive relays function in the usual manner to control the sequential setting of the lamp display registers of the positional equipment.

In the second modification of the invention but three gaseous conductor tubes are employed, two of which function in the same manner as the corresponding tubes of the first modification in ,response to the application of either low or high negative potential impulses to the tip conductor nection of heavy negative potential to the ring conductor and ground to the tip conductor.. The three responsive relays associated with the tubes function to control the sequential setting of the lamp display registers and to record the receipt of a final heavy positive impulse in the samemanner as the corresponding impulse responsive relays of the Powell patent hereinbefore referred to.

For a more complete understanding of the invention reference may be had to the following detailed description taken in connection with the attached drawings in which:

Figs. 1 and 2 show such portions of a central ofiice sender as are necessary to an understanding of the invention; Fig. 1 showing relay equipment for generating and transmitting code impulses for setting up line designations on indicating equipment in a manual office and transfer relays for successively associatingthe impulsing equipment with the digit register of Fig. 2, and Fig. 2 showing a register of the cross-bar type upon which the numerical and stations digits of telephone designations may be registered.

Fig. 3 shows a portion of the call indicating equipment of a manual office, and

Fig. 4 shows a modified form of the call indicating equipment;

For a complete disclosure of the invention, Fig. 2 should be placed beneath Fig. 1, and either Fig. 3 or Fig. 4 should be placed to the right of Fig. 1.

Since the invention relates more particularly to the use of gas-filled tubes as responsive relays for receiving call indicator code impulses and for controlling the registration and indication of the digits of line designations in accordance therewith, only so much of a sender for generating and transmitting the code impulses in accordance with digits registered in the sender has been disclosed as is considered necessary to an understanding of the invention. For this purpose a portion of the cross-bar register and code impulse generating and transmitting equipment of a typical sender has been disclosed. For a complete disclosure of a sender of this type reference may be had to the application of R. Raymond hereinbefore referred to. In this connection it may be noted that the impulsing equipment has been slightly modified to generate impulses of a character to which the gas-filled tubes are particularly responsive.

The call indicator equipment of Fig. 3 is substantially identical to the similar equipment disclosed in Patent 1,968,420, granted to A. C. Powell hereinbefore referred to with the exception that the two polarized relays and the marginal relay which respond to code impulses transmitted thereto from a sender, have been replaced by four gas-filled tubes and anode relays.

The call indicator equipment of Fig. 4 is identical to the similar equipment disclosed in Fig. 3 with the exception that the four tubes and as sociated anode relays which respond to code impulses transmitted thereto have been replaced by three gas-filled tubes and associated relays.

In both Figs. 3 and 4, the operators position equipment has been indicated by small rectangles in order to simplify the drawings. It is to be understood that the trunk incoming from the sender terminates at the operators position in a plug by means of which the operator may complete a call incoming over the trunk to a desired subscribers line whose number is indicated on her indicating equipment and that the position equipment comprises the usual assignment key and relays by means of which the operator may cause the association of her indicating equipment with the incoming trunk and signal the sender to transfer thereto the line designation registered in the sender.

It is believed that the invention will be best understood if the operationthereof is described in connection with a typical call. It will therefore be assumed that a calling subscriber has dialed the line designation MA3-10457 and that this line designation has been registered on the register of the sender, a portion of this register being illustrated in Fig. 2. Since this invention is not concerned with the registration of the oiiice code MA3 and the manner in which the sender controls the setting of selector switches to extend a connection to this ofiice, in the case assumed in the manual office of Fig. 3, the portion of the register upon which the office code designation is registered, the selector controlling apparatus of the sender and the selector switches have been omitted and only that portion of the sender register upon which the numerical digits and the stations letter are registered has been illustrated.

I Under the assumption that the numerical designation registered was 10457, the cross-point contact sets 200, 20I, 202, 203 and 204 have been operated to register the ten thousands digit 1, the

thousandsdigit 0, the hundreds digit 4, the tens digit 5 and the units digit 7 in a manner fully set forth in the Raymond application hereinbefore referred to.

In the establishment of the connection to the wanted manual ofiice of Fig. 3, after the selector switches (not shown) have been set by the sender to select idle trunk 300 and 30I extending thereto, with the class relays 205, 206 and 201 operated for a call of this class, a trunk test circuit is establihed to test the selected trunk to determine if the trunk is in condition to be used for the connection. This circuit may be traced in part from the tip conductor 300 of the trunk back to the sender thence over conductor I 00, winding of overflow relay IOI, winding of trunk test relay I02, lower back contact of relay I03, conductor I04, left contact of class relay 201, conductor E05 to the ring trunk conductor 30L If the trunk is in proper condition to complete the connection, relay I02 operates, but overflow relay IOI does not. Relay I02 closes an obvious circuit for relay IOIi which causes the operation of relay I01 in a circuit extending from battery, winding of relay I07, contact of relay I06, back contact of relay I 03 to ground. With relay I01 operated, relay I06 is now locked in a circuit extending over the inner upper front contact of relay I01, upper back contact of relay I03, to ground and a circuit is established from battery, winding of relay I09, conductor IIO, right contacts of class relays 206 and 207, conductor III, middle upper front contact of relay I? to ground at the back contact of relay IOI. Relay E20 upon operating looks over its inner lower front contact, to ground at the back contact of relay I08. At its inner upper front contact it establishes an obvious operating circuit for relay H2 and at its upper and lower contacts removes resistances II3 and H4 from the circuits of pulsing relay II5 preparing it to operate at a fast rate.

Relay II2 upon operating causes the operation of relay I 03 which opens the locking circuit of relays I00 and I01, but these relays remain operated under the control of relay I02. Relay I03 at its lower back contact, opens the fundamental circuit above traced, but when relay IIZ operated, a substitute circuit was closed over conductor 300, conductor E00, lower front contact of relay I03, winding of relay I02, lower front contact of relay I0I, lower front contact of relay IIZ, conductor I05, to conductor 30L thus holding relay I02 operated under the control of the manual operator until the operator assigns the trunk.

Relay I 03 also closes a shunt around the winding of overflow relay IOI over its lower front contact. To prevent the release of relay I01 and the start of pulsing before the proper conditions have been established, a holding circuit is provided for relay I06 over the inner upper front contact of relay I07, the lower back contact of relay III, the upper back contact of relay I I9, upper front contact of relay II 2 to ground, relay I06 holding relay I07 operated over the previously traced locking circuit.

Relay H5 is a non-biased, condenser-timed, polarized relay which closes its front contact when energized in one direction, closes its back contact when energized in the other direction and leaves either contact closed when not ener-. gized. When current is first passed through its upper winding in either direction, its force is neutralized by an opposing current over the lower winding caused by the discharge of the timing condenser I and its recharge in the opposite sense. When the condenser has been discharged and recharged, current ceases to flow in the lower winding and the upper winding causes the armature to move over from one contact to the other. The alternate back and forth movement of the armature can be retarded as desired by selecting the proper capacity and resistances. Both ends of both windings are normally connected to battery, the left ends in common through resistance I2I. The right end of the upper winding is connected over the lower front contact of relay I 09, resistance I22 and resistance II8 to battery, while the right end of the lower winding is connected through condenser I20, the upper front contact of relay I09, resistance M8 to battery. By shunting one or the other battery connection with ground, current is caused to flow through the upper winding in one direction or the other and in the lower winding always in the opposing direction. With relays H5 and H6 normal, resistance I22 is shunted over the back contacts thereof and with either relay operated, this resistance is introduced in series with the upper winding of relay I I5 to delay the closure of its back contact and thus equalize alternate pulses.

When relay II2 operated, it connected ground over its inner lower front contact to the armature of relay H5 and to the upper armature of relay I It thereby connecting ground over the back con tacts of these armatures in shunt of battery through resistance II8. Therefore relay H5 closes its front contact extending ground to the winding of relay H5. Since relay II! is not operated at this time, the operation of relay H6 is ineffective to release relay II5 and relays H5 and II5 remain operated ready to start pulsing. Since relay I03 is operated, the circuit closed at the lower contact of relay H6, extends from ground at that contact over the upper front contact of relay I03, inner upper normal contacts and winding of relay II9, resistance I23, to battery. The circuit also extends to the winding of relay I24 but this relay is shunted over its inner upper back contact so that relay IIS operates alone, looking over its alternate contacts to ground over the inner lower contacts of relay I I2. With relay H5 operated and either relay I24 or relay I25 non-operated, a circuit is closed from ground over the front contact of relay II5, outer upper back contact of relay I 2 5, or lower back contact of relay I25, winding of relay I26 to battery.

When the operator at the manual office assigns the trunk 300 and 30I, battery and ground are removed at the position circuit 302 in the usual manner and conductors 300 and 30I are connected to conductors 304 and 303, respectively. Relay 329 is also operated from the position circuit 302 at this time. Relay I02 now releases in turn releasing relays I06 and I01. With relay II2 operated and relay I01 released, the fundamental tip conductor 304 is extended over conductors 300 and I90, middle upper front contact of relay II 2, upper back contact of relay I01, upper back contact of relay I25, to conductor I30. The fundamental ring conductor extends from conductor 303 over conductors 30! and I05, lower front contact of relay I I2, inner lower back contact of relay m1, inner lower back contact of relay I25 to conductor I3I. The release of relay I01 also closes a circuit from ground at the inner lower contact of relay IIZ, lower back contact of relay I61, winding of relay II1 to battery. Relay II1 operates and locks over its inner lower front contact to ground at the contacts of relay I I2, at its upper back contact removes the shunt from battery through resistance H8, and connects the upper front contact of relay II6 over its inner upper front contact in shunt of battery through resistance I2I thereby starting relays I I5 and I I5 to pulsing. Relay I I5 opens its front contact releasing relay IS which opens the shunt around the winding of relay I24 and that relay operates. When relay H5 next closes its lower contact, it connects ground over the inner upper front contact of relay I24 to resistance I23 in shunt of the winding of relay H3. Relay II9 releases, but relay I24 is held operated over the inner make-nefore-break contacts of relay H9, first to the locking ground of relay H9 and then to ground at the contact of relay II6. When relay II 6 releases, relay I24 also releases. Relays I I9 and I24repeat this cycle of operations under the control of relay II6 until the designation has been completely transmitted. Each complete cycle generates four impulses to transmit one digit as follows:

Relay I26 operates in parallel with relay II6 being operated for the odd pulses and released for the even pulses. At each operation relay I26 closes a circuit from battery through the winding of relay i322, upper contact of relay I26, upper front contact of relay I I1, to ground at the middle lower contact of relay II2. Relay I26 serves to alternately connect ground to conductor I3I thence over the fundamental ring for the odd pulses and to conductor I33 thence over the fundamental tip for the even pulses. On the first or odd pulse with relay I26 operated, the fundamental ring conductor is connected to ground over the front contact of relay I26 and either the low inductance coil I 33 or the high inductance coil I34 is energized in a circuit extending from ground at the make contacts of relay I26, and either the low inductance coil I33 or the high inductance coil I34 is energized in a circuit extending from ground at the make contacts of relay I26, inner upper back contact of relay I25 to the armature of relay I35, thence through the coil I33 or the coil I34 dependent upon the condition of relay I35, thus completely saturating the core of the energized coil. At the same time the fundamental tip conductor is either momentarily connected to ground over the back contact of relay I28 and the back contact of relay I32, or to the winding of the previously charged inductance coil I21, dependent on whether relay I28 has or has not been operated from the dial register to denote either a blank or light positive pulse.

On the second or even pulse with relay I26 unoperated, ground is connected over the normal contacts of relay I26 to the fundamental tip conductor and the winding of the previously charged low inductance coil I 33 or the winding of the charged high inductance coil I34, is connected to the fundamental ring conductor dependent on whether relay I35 has or has not been operated from the dial register to denote a heavy or light negative impulse.

On the third or odd pulse with relay I26 operated, the fundamental ring conductor is again connected to ground over the front contact of relay I 26 and either the low inductance I33 or the high inductance coil I34 is again energized dependent upon the condition of relay I35. At the same time the fundamental tip conductor is either momentarily connected to ground over the back contact of relay I28 and the back contact of relay I32 or to the winding of inductance coil I21 dependent upon whether relay I28 has not or has been reoperated from the dial register to denote either a blank or light positive pulse.

On the fourth or even pulse with relay I26 uno-perated ground is connected over the normal contacts of relay I26 to the fundamental tip conductor and the winding of the previously charged low inductance coil I33 or the winding of the charged high inductance coil I34 is connected to the fundamental ring conductor dependent upon whether relay I35 has or has not been operated from the dial register to denote a heavy or light negative pulse.

In general relay I28 is operated in a circuit extending from battery through its winding to the lower armature of relay I24. With this relay released either before pulsing or in the fourth pulse period, the circuit extends over conductor I36 to contacts in the No. I and No. 6 levels of the dial register to operate relay I28 in readiness to send out a positive pulse in the first pulse period as called for by the code for digits I and 6. With relay I24 operated in the second pulse period, the circuit extends over conductor I31 to contacts in the No. 4 level of the dial register to operate relay I28 in readiness to send out a positive pulse in the third pulse period. Similarly the circuit of relay I35 extends to the lower armature of relay II9. Relay I I9, being operated in the first pulse period, the circuit of relay I35 is extended over conductor I38 to contacts in the No. 2 and No. 1 levels to prepare for sending a heavy negative pulse in the second pulse period. When relay II9 releases in the third pulse period, the circuit of relay I35 extends over conductor I39 to contacts in the No. 5, No. 6, No. 1, and No. 8 levels.

To save contacts on the dial register, when a heavy negative pulse follows a positive pulse directly as in the codes for the digits 3, 8, and 9, relay I40 is operated over conductor MI and contacts of the No. 3 and No. 8 levels of the dial register and relay I42 is operated over conductor I43 and contacts of the No. 9 level to supply additional circuits for operating relays I28 and I 35. Conductors I36 to I39 and MI also extend to contacts in levels other than those mentioned above.

' These contacts occur in the thousands and stations verticals which are cross-connected according to different code arrangements as will appear from the following table, in which "n represents a light negative pulse, N a heavy negative pulse, p a positive pulse and a blank pulse.

Regular Thousands Stations digit digit digit 0 0 0 -n-m, l 2 1 gm'n 2 4 W(9) N-II. 3 6 R (7) pN-n 4 8 I (5) npn 5 l M(6) -nN 6 3 pnN 7 6 N-N 8 7 pN-N 9 9 'npN At the manual omce of Fig. 3, the tip and ring conductors 304 and 303 are associated with ,four gas-filled tubes, each having a cathode heated by a filament, a control electrode or grid and an light negative code impulse.

anode. The ring conductor 303 is connected to the anodes of tubes 305 and 306 through anode relays 300 and 3I0, respectively, and to the cathodes of tubes 301 and 308, and the tip conductor 304 is connected to the cathodes of tubes 305 and 306 and to the anodes of tubes 301 and 300 through anode relays 3H and 3I2, respectively. The grid of each tube is biased negatively by the connection thereof to the negative terminal of a biasing battery, the grids of tubes 306 and 301 being biased to a lower negative potential than the grids of tubes 305 and 308. Tube 301 is thus biased soas to ionize when low negative potential is applied to its cathode over the ring conductor 303 and ground potential is applied to its anode over the tip conductor 304 and thus responds to a Tube 308 having a higher negative bias will ionize at the same time as tube 301 when high negative potential is applied to its cathode over the ring conductor 303 and ground potential is applied to its anode over the tip conductor 304 and thus responds to a heavy negative code impulse. Tube 306 is so biased as to ionize when low negative potential is applied to its cathode over tip conductor 304 and ground potential is applied to its anode over ring conductor 303 and thus responds to a light positive code impulse while tube 305 having a higher bias ionizes at the same time as tube 306 when high negative potential is applied to its cathode over tip conductor 304 and ground potential is applied to its anode over ring conductor 303 and thus responds to a heavy positive code impulse. None of the tubes will ionize when ground potential is applied to both conductors 303 and 304 as on blank pulses.

Relay 3II controls the operation and release of relays 3I3 and 3I'4 in cycles which in turn control the transfer relays 3I5 to 324 inclusive for associating the groups of digit register relays with the contacts of relays 309, 3 I 0 and 3I2.. Only one group of relays 325 to 328, constituting the stations register, has been disclosed, other groups of register relays being connected to contacts of the transfer relays in the manner disclosed in Patent front contact of relay I44 to ground in any suitable manner. Since a five digit numerical designation 10457 has been registered, when the fifth digit was registered a circuit was closed from battery through the windings of transfer relays I46 and I41, conductor I6I, middle contacts of the No. 1 contact set 204 in the stations vertical, back contact of relay 209, cross-point contact of the No. 4 contact set 202 in the tens vertical, crosspoint contact of the N0; 0 contact set I in the hundreds vertical, cross-point contact of the No. I contact set 200 in the thousands vertical, front contact of relay 2I0, which operated when the fourth numerical digit was registered, conductor 2| I to ground over the inner upper front contact of transfer relay I44. Relays I46 and I41 look over the inner upper front contact of relay I46 to ground.

Since transfer relays I44 to I41, inclusive, are operated and the ten thousands digit I has been registered on the thousands vertical, ground over 7 the inner upper front contact of relay I I2 and conductor I58 is extended over the lower front contacts of transfer relays I44 and I46 and the lower back contact of transfer relay I48 to one set of contacts in the thousands vertical and over the lower front contacts of transfer relays I45 and I41 and the lower back contact of transfer relay I49 to another set of contacts of the thousands vertical for controlling the operation of relays I28, I35, I40 and I42.

With the cross-point contact set 200 operated, to register the ten thousands digit I, a circuit is efiective just prior to the first pulse period at which time relay I24 is released for operating relay I28. This circuit extends from battery, Winding of relay I28, lower back contact of relay I24, conductor I36, upper back contact of relay I56, conductor I60, middle contact of cross-point 200, conductor 2I2, lower back contact of relay I48, lower front contacts of relays I46 and I44, conductor I53, thence as traced to ground. 4 Therefore when relay I 26 operates during the first pulse period, the ring conductor 303 is grounded and a surge of low negative potential is applied from inductance coil I21, over the front contact of relay I23 and thence as traced to the tip conductor 304, coil I21 having charged as previously described prior to the first impulse period. Tube 300 will now ionize since the low negative potential applied to its cathode over conductor 304 will overcome the low negative bias on its grid and its anode is supplied with positive or ground potential over conductor 303. Tube 305 having a heavier negative bias will not ionize and tubes 301 and 308 will not ionize since negative potential is applied to their anodes over conductor 304 and positive potential is applied to their cathodes over conductor 303.

With, tube 306 ionized, relay 3! is operated in the cathode-anode circuit thereof extending from the negative terminal of battery, coil I21, front contact of relay I20, upper back contact of relay I25, thence as traced to conductor 334, cathode and anode of tube 303, winding of relay 3I0, conductor 303, thence as traced to the inner lower back contact of relay I25, conductor I3I to ground at the alternate contacts of relay I26. Relay 3I0 upon operating closes a circuit from ground at the lower front contact of relay 329, conductors 330, 33I and 332, contacts of relay 310, upper back contact of relay 3 I3, upper back contact of transfer relay 3I5, lower winding of register relay 325 to battery. Relay 325 operates and locks in a circuit from battery through both of its windings and its inner upper front contacts to ground on conductor 330.

. Since during the first pulse period there is no circuit effective for relay I35 over cross-point 200 when relay I I9 operates, relay I26 upon releasing during the second pulse period removes ground potential from the ring conductor 303, thus causing the deionization of tube 306 and the release of relay 3I0. With relay I26 released it connects ground to the fundamental tip conductor 304 and with relay I35 unoperated, a surge of low negative potential is applied from inductance coil I33 to the fundamental ring conductor 303, this coil having been charged aspreviously described during the first pulse period. Tube 301 will now ionize since the low negative potential applied to its cathode over conductor 303 will overcome the low negative bias on its grid and its anode is supplied with ground or positive potential over the tip conductor 304. Tube 308 having a heavier negative bias will not ionize and tubes 305 and 306 will not ionize since negative potential is applied to their anodes over conductor 303 and positive potential is applied to their cathodes over I conductor 304.-

With tube 301 ionized, relay 3| I is operated in the cathode-anode circuit thereof extending from the negative terminal battery, coil I33, back contact of relay I35, inner upper and inner lower back contacts of relay I25, thence as traced to conductor 303, cathode and anode of tube 301, winding of relay 3, conductor 304, thence as traced to the upper back contact of relay I25, conductor I30 to ground at the normal contacts of relay I26. Relay 3 upon operating closes a circuit from ground on conductor 332, contact of relay 3| I, lower back contact of relay 3I4, winding of relay 3I3, lower winding of relay 3I4 to battery. Relay 3I3 operates but the lower winding of relay 3| 4 being marginal, relay 3 I4 does not operate. Relay 3| 3 upon operating closes a short circuit around the upper winding of relay 3| 4, extending from conductor 332, lower contact of relay 3I3, upper winding of relay 3I4, lower back contact of relay 3I4, contact of relay 3| I to conductor 332.

During the second pulse period no circuit is effective over cross-point 200 for relay I28 and thus during the third pulse period when relay I26 operates, both the tip and ring conductors 304 and 303 are grounded, resulting in a blank pulse. to this blank pulse and since ground potential is now supplied to the cathode of tube 301 in place of negative potential tube 301 deionizes releasing relay 3. Upon the release of relay 3 the shunt around the upper winding of relay 3I4 is removed and relay 3I4 now operates in series with relay 3I3 in a circuit extending from battery, lower winding of relay 3I4, winding of relay 3I3, upper winding of relay 3I4, lower contact of relay 3 I3 to ground on conductor 332. Relay 3I4 upon operating closes a circuit from ground on conductor 332 upper front contact of relay 3I4,

upper back contact of transfer relay 3| 6, winding ,of transfer relay 3I5 to battery. Relay 3I5 operates and locks in a circuit from battery through its winding and the winding of relay 3|6, inner lower front contact of relay 3I5 to ground on conductor 332, but relay 3|6 being shunted so long as relay 3I4 remains operated, does not operate in this locking circuit.

At the sender with relay I35 unoperated and relay I26 operated, the low inductance coil I3 is recharged in a circuit extending from bat- None of the tubes will ionize in response 7 tery, winding of coil I33, back contact of relay I35, inner upper back contact of relay I25, conductor I3| to ground at the alternate contacts of relay I26. With relay I I9 released during the third pulse period, ground is connected over the upper front'contact of relay II2, upper back contact of relay I I9, lower front contact of relay I I1, conductor I59, upper front contacts of transfer relays I45 and I41, upper back contact of transfer relay I49, winding of transfer relay I48 to battery. Relay I48 operates, locking in a circuit extending from battery through its winding and the winding of relay I49, inner upper front contact of relay I48 to ground at the upper contact of relay I46. Relay I49 does not operate in this locking circuit since its winding is shunted so long as relay II9 remains released and connects ground to conductor I59. Relay I48 upon operating disconnects conductor I58 from a thousands vertical of the dial register and connects it over the lower contacts of relays I44, I46 and I 48 and the lower back contact of relay I50 to a hundreds vertical of the dial register, preparing the circuits which control the first and second pulse periods of the next or thousands digit.

Since no circuit is effective over cross-point 200 for relay I35, during the third pulse period when relay H9 is released, when therefore relay I26 releases during the fourth pulse period, ground potential isconnected to the fundamental tip conductor 304 and with relay I35 unoperated, a surge of lowpotential is applied from induction coil I33, to the fundamental ring conductor 303, coil I33 having been placed in a charged condition as previously described during the third pulse period. Tube 301 will now ionize, tubes 305, 306, and 308 remaining deionized. Relay 3| I now operates in the cathode-anode circuit of tube 301, previously traced, and connects ground from conductor 332 over its contacts to the lower front contact of relay 3 I4 holding relay 3I4 and shunting down relay 3I3. The impulses transmitted during the first four impulse periods have therefore resulted in the operation and locking of one relay 325 of the stations register.

At the end of the fourth pulse period relay I I9 is reoperated thus permitting transfer relay I49 to operate in the locking circuit of relay I48 and transfer the connection of conductor I58 from a thousands vertical of the dial register to a hundreds vertical over the lower front contacts of relays I45, I41 and I49 and the lower back contact of relay I5I preparing the circuits which control the third and fourth pulse periods of the next or thousands digit.

Since the thousands digit registered was zero and the cross-point contacts 20| are operated, there'are no circuits effective for relays I28, I35, I40 and I42 during the next four pulse periods and only two light negative impulses are transmitted characteristic of the digit zero. During the first of these pulse periods, relay I26 operates and removes ground potential from conductor 304 and the anode'of tube 301 thus deionizing this tube and releasing relay 3. Relay 3II upon releasing opens the locking circuit of relay 3I4 which also releases removing the shunt from transfer relay 3|6 which now operates. With both relays 3I5 and 3|6 now operated the circuit from the contacts of relays 3I0 and 3I2 are transferred from relays of the stations register to relays of the thousands register (not shown).

During the second pulse period with relay I26 released, tube 301 reionizes in the same manner as previously described causing the operation of 3, register.

relays 3I I 'and3I3. When relay I26 reoperates during the third pulse period tube 30'! deionizes and releases relay 3| I. thus permiting relay 3I4 .to operate in series with relay 3 I 3.- The operation a of relay 3I4 closes a circuit from ground on conductor 332 over its upper front contact, the upper front contact of relay 353, the upper back contact of relay M8 to battery through the winding of relay 3II. Relay 3I'I operates and locks in series with the winding of relay 3I8 and its own inner lower front contact to ground on conductor 332, but relay 3 I 8 being shunted over the contacts of relay 3M does not operate at this time. When relay I26 releases during the fourth pulse period tube 301 reionizes and operates relay 3! I which shunts down relay 3I3 and holds relay 3M operated. Since neither tube 303 nor 308 has been ionized during these four pulse periods and relays 3H] and 3I2 have not operated, no relays of the thousands register (not shown) are operated.

At thesender during the third of these pulse periods with relay M9 released, ground is connected to conductor I53, thence over the upper front contacts of relays I45, I41 and I49, the upper back contact of relay I5I, winding of relay I5fl to battery. Relay I53 operates and locks in a circuit through the winding of relay I5I, the inner upper contacts of relay I50 and the upper contact of relay I48 to ground and disconnects conductor I58 from a hundreds vertical of the dial register and connects it over the lower front contacts of relays 544, I46, I48 and I5!) and the lower back contact of relay I52 to a tens vertical of the dial register. The circuits are now prepared which control the first and second pulse period of the next or hundreds digit. At the end of the fourth pulse period relay IIil reoperates thus permitting relay I5I to operate in the locking circuit of relay I50. Relay I5I upon operating disconnects conductor I58 from a hundreds vertical of the dial register and connects it over the lower front contacts of relays I45, I41, I49 and I5I and the lower back contact of relay I53 to a tens vertical of the dial The circuits are now prepared which control the third and fourth pulse periods of the next or hundreds digit.

The next digit to be transmitted is the hun- .dreds digit 4 and since no circuit has been made effective over cross-point 202 for relay I28 during the previous fourth pulse period, the operation of relay I25 during the first pulse period first removesground from the tip conductor 334 to cause the deionization of tube 301 and the consequent release of relays 3H and 3I4. Relay 3I4 upon releasing now permits the operation of relay H8 in the locking circuit of relay 3I'I. With both relays 3II and 3I8 now operated, the circuits from the contacts of relays 3IIl and 3I2 are transferred from relays of the thousands register to relays of the hundreds register (not shown). Relay I26 upon operating also connects ground to both the tip and ring fundamental conductors resulting in a blank impulse to which none of the tubes responds. During the first pulse period there is no circuit effective over cross-point 232 for relay I35 when relay "H9 operates and therefore, during the second pulse period when relay I26 releases, ground is connected to the tip conductor 304 and a surge of low negativepotential is applied from inductance coil I33 to the ring conductor 353 resulting in the ionization of tube 301 and the operation ofrelays 3II and3l3.

, During the second pulse period with relay I24 operated a circuit is established from ground on conductor I58, thence as traced to the lower front .mits the operation of relay 3I4. Relay 3I4 upon operating closes a circuit from ground on conductor 332 over its upper front contact, thence as traced to the upper front contact of relay M8,

the upper back contact of relay 326 to battery 4 .through the winding of relay (H9.

Relay 3I9 locks in a circuit through the winding of relay 32B and the inner lower front contact of relay 3I9 to ground on conductor 332, but relay 323 being shunted does not operate at this time. By the operation of relay I25 ground is also applied to the ring fundamental conductor 3% and a surge of low negative potential is applied from the low inductance coil I21 to the fundamental tip conductor 354. This results in the ionization of tube 303 and the operation of relay 3H3. With relays 3H] and 3I3 both operated a circuit is established from ground on conductor 332, contacts of relay 3E5, upper front contact of relay 3l3, inner lower front contacts of relays SIG and 3I8, inner lower back contact of relay 323 to the C relay of the hundreds register (not shown).

During the third impulse period relay Mil releases and connects ground over conductor I59, thence over the upper front contacts of relays I45, I41, I49 and l5l, the upper back contact of relay I53 to battery through the winding of relay I52. Relay I52 operates and locks in a circuit through its winding and the winding of relay I53, the inner upper front contact of relay I52 to ground at the upper front contact of relay I50 and disconnects conductor 958 from a tens vertical of the dial register and connects it over the lower front contacts of relays I44, I45, I48, I53 and W2 and the upper back contact of relay I54 to a units vertical thus preparing the fourth pulse period it first disconnects ground from the ring fundamental conductor 333 thus deionizing tube 34? and releasing relay 3Ill and then .connects ground to the tip conductor 304 and applies a surge of low negative potential from inductance coil I33 to the ring conductor. Tube 331 now ionizes operating relay 3 which shunts down relay 353 and holds relay 3I4 operated. The impulses thus transmitted for the hundreds digit 4 have resulted in the operation of only the C relay of the hundreds register.

At the end of the fourth pulse period relay I I9 reoperates thus permitting relay 053 to operate in the locking circuit of relay I52. Relay I53 upon operating disconnects conductor I58 from a tens vertical of the dial register and connects it over the circuit traced to the lower front contact of relay I5I, the lower front contact of relay I53 and the lower back contact of relay 555 to a tens vertical of the dial register. The circuits are. now prepared which control the third and fourth pulse periods of the next or tens digit.

The tens digit recorded. was 5 and thus the contacts at cross-point 203 are operated. Since there is no circuit effective over these cross-point contacts when relay I24 releases during the previous fourth pulse period, relay I28 is not operated and when, therefore, relay I26 operates during the first pulse period it first removes ground from the tip fundamental conductor 304 to deionize tube 301 causing the release of relays 3H and 3I4. The release of relay 3I4 permits the operation of relay 320 in the locking circuit of relay 3I9. Relay I26 then connects ground to both the tip and ring fundamental conductors. No tubes, therefore, become ionized.

During the first pulse period when relay I I9 operates there is no effective circuit for relay I35 over the cross-point 203 and therefore when relay I26 releases during the second pulse period ground is applied to the tip fundamental conductor 304 and a surge of low negative potential is applied to'the ring conductor 303 resulting in the ionization of tube 30'! and the operation of relays 3H and 3 I3. During the second pulse period there is no effective circuit o-ver cross-point 203 for relay I28 and thus when relay I26 operates during the third pulse period, ground is first removed from the tip fundamental conductor 304 thus deionizing tube 301 and releasing relay 3 thereby permitting the operation of relay 3| 4. Relay 3I4 upon operating closes a circuit from ground on conductor 332 over its upper front contact and the upper front contacts of relays 3I6, 3I8 and 320, the upper back contact of relay 322 to battery through the Winding of relay 32 I. Relay 32I operates and locks in series with the winding of relay 322 to ground over its inner lower front contact, but relay 322 being shunted does not operate at this time. Relay I26 then connects ground to both the tip conductor 304 and the ring conductor 303 resulting in a blank pulse. No tube will therefore ionize.

During the third pulse period relay II 9 releases and connects ground over conductor I59, thence as traced to the upper front contact of relay I5I, upper front contact of relay I53, upper back contact of relay I55 to battery through relay I 54. Relay I54 operates and locks in a circuit through the winding of relay I55, the lower contact of relay I54 to ground at the upper contact of relay I53 and disconnects conductor I58 from a units vertical of the dial register and connects it over the circuit previously traced to the lower front contact of relay I52, thence over the upper front contact of relay I54 and the lower back contact of relay I56 to a stations vertical of the dial register. The circuits are now prepared which control the first and second pulse periods of the last or units digit. Upon releasing, relay I I9 also establishes a circuit for relay I35 extending from ground on conductor I58, thence as traced to the lower front contact of relay I5I, lower front contact of relay I53, the lower back contact of relay I55, conductor 2I4, cross-point 203, conductor I 39, lower back contact of relay II9 to battery through the windingof relay I35. When relay I26 releases during the fourth pulse period it connects ground to the fundamental tip conductor 304 and applies a surge of high negative potential from the inductance coil I34, front contact of relay I35, thence as traced to the fundamental ring conductor 303. -Both tubes 301 and 308 therefore ionize operating relays 3| I and 3I2. Relays 3I I shunts down relay 3I3 and holds relay 3I4 operated and relay 3I2 closes a circuit connected from ground on conductor 332 over its contact, the inner upper front contact of relay 3I4, the inner upper front contacts of relays 3I6, 3I8 and 320, lower back contact of relay 322 to the D relay of the tens register (not shown). At the end of the fourth pulse period relay II9 reoperates thus permitting relay I55 to operate in the locking circuit of relay I54. Relay I55 upon operating disconnects conductor I58 from a units vertical of the dial register and connects it over the circuit previously traced to the lower front contact of relay I55, the lower back contact of relay I51 to a stations vertical of the dial register. The circuits are now prepared which control the third and fourth pulse periods of the last or units digit.

The units digit recorded was I and thus the contacts at cross-point 204 are operated. Since there is no circuit effective over these cross-point contacts when relay I24 releases during the previous fourth pulse period, relay I28 is not operated. When therefore, relay I26 operates during the first pulse period, it first removes ground from the'tip fundamental conductor 304 to deionize tubes 30'! and 308 causing the release of relays 3| I, 3I2 and 3I4, the release of relay 3I4 permitting relay 322 to operate in the locking circuit of relay 32I. Relay I26 then connects ground to both the tip and ring fundamental conductors. No tubes, therefore, become ionized.

During the first pulse period when relay II9 operates, a circuit is established from ground on conductor I58, thence as traced to the lower front contact of relay I52, upper front contact of relay I54, lower back contact of relay I 56, conductor 2I5, contacts of cross-point 204, conductor I38, front contact of relay II9, winding of relay I35 to battery. When relay I26 releases during the second pulse period with relay I35 operated, ground is applied to the tip fundamental conductor 304 and a surge of high negative potential is applied to the ring conductor 303 from inductance coil I34 resulting in the ionization of both tubes 30! and 308 and the operation of relays 3| I, 3I2 and 3I3. Relay 3I2 upon operating closes a circuit from ground on conductor 332 over its contacts, the upper back contact of relay 3I4, the lower front contacts of relays 3I5, 3H, 3I9 and 32I to the B relay of the units register (not shown). During the second pulse period there is no effective circuit over cross-point 204 for relay I28 and thus when relay I26 operates during the third pulse period, ground is first removed from the tip fundamental conductor 304 thus deionizing tubes 30'! and 308 and releasing relays 3H and 3 I 2. Relay 3| I upon releasing permits the operation of relay 3I4 which closes a circuit from ground on conductor 332 over its upper ,front contact, thence as traced to the upper front contact of relay 320, upper front contact of relay 322, winding of relay 323 to battery. Relay 323 operates and locks in series with the winding of relay 324 and its own upper front contact to ground on conductor 332, but relay 324 being shunted does not operate at this time. Relay I26 then connects ground to both the tip conductor 304 and the ring conductor 303 resulting in a blank pulse. No tube will, therefore, ionize.

During the third impulse period, relay II9 releases and connects ground over conductor I59, thence as traced to the upper front contact of relay I53,, upper front contact of relay I55, upper back contact of relay I51, winding of relay I56 to battery. Relay I 56 operates and locks in a circuit through the winding of relay I51, the upper front ionize operating relays 3H and 3| 2.

contact of relay 15.6 to ground and disconnects conductor 1.58 from :a stations vertical. Upon releasing, relay 1-0 also establishes a circuit for relay I35 extending from ground on conductor I58, thence as traced to the lower front contact vof relay I53, lower front contact of relay I55, lower back contact of relay I51, conductor 2H5, contacts of cross-point 204, conductor l39,-lower back contact of relay M3 .to battery through the winding of relay I35. When relay I26 releases during the fourth pulse period, it connects ground to the fundamental tip conductor 304 and applies a surge of high negative potential from the inductance coil I134, front contact :of relay I35, thence as traced to the fundamental ring conductor 303. Both tubes .30! and 308 therefore Relay 3' "shunts down relay 3I3. and holds relay 3I-4 operated and relay 3I2 closes a circuit from ground on conductor 332 over its contact, the inner upper front -contact of :relay 3-.I4, thence as traced to the inner upper front contact of relay 3210, inner upper .front 'contact of relay 322 to the D relay of the units register (not shown).

At the end of the fourthpulse period relay H9 reoperates thus permitting relay I51 to operate coil 13-4 extending from battery, winding of coil I34, inner upper front contact of relay 1I25 to "ground at the alternate contacts of relay 126.

Ground fromthe Lfront contact of relay I26 is also.appli'ed'over=the upper front contact of relay .1125 to the tip fundamental conductor 304 and to the ring fundamental conductor 303 from the back contact of relay 132, back contact of relay over the inner lower front contact of relay I25, thence .as traced. 3

During the second pulse period when relay I26 releases ground is connected to the ring fundamental conductor 303 from the normal contacts of :relay 4123 and over the lower front contact of relay I 25 .and ground :being removed from the tip fundamental conductor by the-operation of relay 12.6., -a-.surge ofrhigh negative potential is app-lied from the "charged high inductance coil I34 over the innerproper and outer upper front contacts of relay I25 to the tip .conductor 304 thustransmitting atheavy positive impulse. With high negative potential applied to the cathodes of tubes 3.0.5-and 3 .06 over-conductor 304, both tubes ionizeoperating relays 3.09-and 3I0. Relay 310 is without function at this time, butrelay 309 -upon operating {closes -a circuit from ground on condnctor 33-2 icontacts of relay 309, contacts of relay I324, =winding of relay 333 to battery. Relay 333 operates-and locks in serieswith relay .334, front contacts of-relay3133 to ground-at'therinner lower front .contact of relay 323. With relay I25 operated, relay 123 which is operated during the second and third wpulse periods holds open the circuit of relay :I26.

Whenvrelay H9 releases at the. beginning of the third :pulse period it connects :ground to conductor :LBBrand-thence as traced to the upper front contact of relay I51 to battery through the winding of :relay I08. Relay I08 initiates aseries of operations for releasing the sender and opens the locking circuit .of relay I09 which in turn releases relay H2. Relay 2 opens the fundamental circuit, releases relays .II .1 and J03, removes ground from the pulsing relays H5 and I It, releases relay I25 and opens the holding circuit for relays I I9 .and I24 thereby restoring .the pulsing circuit to normal. The transfer relays of Fig. lare releasedinthe restoration .of the sender. Upon the opening of the fundamental circuit, tubes 305 and 30.3 deionize, releasing relays 300 and M0, relay 33 9 upon releasing permitting relay 334 to operate in the locking circuit .of

relay 333.

Since the manner in which the indicator lamps at the manual omce are lighted in accordance with the operated condition of the digit registers to indicate the called number 1-045? and the manner in which .the operator proceeds to .com-

plete thecall incomingover trunk .300, -.30-I :do .not concern the present invention, reference may be had to "Patent N 0. 1,968,420 hereinbefore referred to for a detailed description thereof.

Fig. 4 shows a modified form of the .call indicator equipment at the manual office which is in most r-espectssimilar to thatshown in Fig. :3 except that three tubes and associated anode relays rather than four tubes and associated relays are employed. Tube 305 and the associated anode relay 309 of Fighsareemployed only to respond to a heavy positive impulse which is transmitted from the .sender following the transmissionof the codes .of impulses corresponding to the .digits of the line designations. .lnFig-e all apparatus which is similar tothatpf Figlfshas been designated by corresponding reference numerals ;and the functions performed by tube 305 and relay 3090f Fig. .3 .are performed .by .tube .301 and relay all through .the reversal .of the connections .of the tip and ring conductors .304 and .303 to .the

cathode and :anodeof .tu-be30l :through .the operationof the last transfer relay .324.

During the reception of .the code impulses for .all of the digits ofla vline designation, relays 3.23 .and 324 .are unoperated and therefore the tip conductor 304 extends over the upper normal contacts .of relay .324lto .the cathode of (tube .306

3| 2 are the same as disclosed in Fig. 3 and the:

control exercised by these relays istherefore :the same .as -;previously described. Thelcircuit [controlled by relay v3H is, however, extended-over the inner .upper .back contacts of relay .324 to the lowerarmature of relay 3M, but until relay 3-24 is operated, relay ,3II functions in the .manner previously described. ,It will be recalled .that during the reception of the code impulses for the last or units digit of the ,line designation all of the transfer relays 3I5 to 323, inclusive, were operated, thatj-relay 3| 4 was also operated and that during the first pulse of theftransmission of the final heavy positive impulse code, relay 3l4 released permitting relay 324 to operate in the locking circuit of relay 323. With relay 324 operated, the connection of the tip and ring:conductors 304 and 303 to the cathodes and anodes of tubes 306, 301 and 1308is reversed and the front contact of anode relay 3H is disconnected from the lower armature of. re ay .314. and connected to the winding of relay 333. when, therefore, the sender impulser connects ground to the ode relay 3!! causes the operation of relay 333 over a circuit extending from ground on conductor 330, front contact of relay 3| l, inner upper front contact of relay 32 4, winding of relay 333 to battery. From this point the circuits of Fig. 4 function inthe same manner as those of Fig. 3. From the foregoing it will be apparent that through the use of gas-filled tubes which are very sensitive to marginal and reversed polarity conditions, the call indicator. equipment may be very accurately controlled over long cable loops and that the marginal and polarized responsive relays heretofore employed for impulse response may be replaced by simple relays Whose adjustmentmay be easily made and maintained. Although gas-filled tubes of the hot cathode type have been disclosed, it will be obvious to those skilled in the art that gas-filled tubes of the cold cathode-type might be employed. It is also to be understood that while a sender having a relay type impulser and a cross-bar type register has been disclosed, any well-known type of sender having an impulser for transmitting call indilcator code impulses might be used with equal i'acility.

f What is claimed is: I,

1. In a signaling system a two-conductor control circuit, a first gaseous conductor tube having itscathode connected, to one conductor of said circuit and its anodeconnected to the other conductor, a second tube having its anode connected to said one conductor and its cathode connected to said other conductor, a relay in th e cathode-anode circuit of each tube, and means for selectively operatingsaid relays by applying negative potential to said one conductor and ground to said other conductor or vice versa.

2. Ina signaling system a two-conductor control circuit, a first gaseous conductor tube having its cathode connected to one conductor of said circuit and its anode connected to the other conductor, a first relay in the cathode-anode circuit of said tube, a second gaseous conductor tube having its anode connected to. said one conductor and its cathode connected to said other conductor, a second relay in the cathode-anode circuit of said second tube, meansfor, operating said first relay by the connection of negative po tential to said one conductor and ground to said other conductor, and means for operating said tive potential and ground to said conductors.

second relay by reversing the connection of nega- 3. In a telephone system an impulse sending device, a registering device, a control circuit extending from said sending device to said registering device, a plurality of ionic relays in said registering device associated with said control circuit, and means controlled by said sending device for transmitting impulses differing in potential and polarity over said control circuit, one of said relays being responsive only to impulses of'heavy potential of one polarity, a second of said relays being responsive to impulses of either 'light or heavy potential of said one polarity, a third of said relays being responsive only to impulses of heavy potential of reverse polarity, and a fourth of said relays being responsive to impulses of either light or heavy potential of reverse polarity.

4. Ina telephone system an impulse sending device, a registering device, a control circuit extending from said sending device to said registering device, a plurality of gaseous conductor tubes in said registering device associated with said control circuit, means controlled by said sending device for transmitting impulses differing in potential and polarity over said control circuit, one of said tubes being responsive only to impulses of heavy potential of one polarity, a second of said tubes being responsive to impulses of either light or heavy potential, a third of said tubes being responsive only to impulses of heavy potential of reverse polarity, and a fourth of said tubes being responsive to impulses of either light or heavy potential of reverse polarity, and registers operable by said tubes.

5. In a telephone system an impulse sending device, a registering device, a two-conductor control circuit extending from said sending device to said registering device, a plurality of ionic relays, certain of said ionic relays having their cathodes connected to one of said conductors and their anodes connected to the other of said conductors,

and others of said ionic relays having their anodes connected to said one of said conductors and their cathodes connected to said other of said conductors, and means controlled by said sending device for transmittingimpulses over said control circuit by applying negative potential to said one conductor and ground to said other conductor or vice versa.

6. In a telephone system an impulse sending device, a registering device, a two-conductor control circuit extending from said sending device to said registering device, a plurality of gaseous conductor tubes in said registering device, certain of said tubes having their cathodes connected 'to one of said conductors and their anodes con nected to the other of said conductors, and others of said tubes having their anodes connected to said one of said conductors and their cathodes connected to said other of said conductors, a relay in the cathode-anode circuit of each tube, registers selectively operable by said relays, and means controlled by said sending device for transmitting impulses over said control circuit for selectively operating said relays by applying negative potential to said one conductor and ground to said other conductor or vice versa. I

'7. In a telephone system an impulse sending device, a registering device, a two-conductor conhaving a difierent breakdown potential, a relay in the cathode-anode circuit of each tube, registers selectively operable by said relays, and means controlled by said sending device for selectively operating said relays by applying light or heavy negative potential to said one conductor and ground to said other conductor or vice versa.

8. In a telephone system an impulse sending device, a registering device, a two-conductor control circuit extending from said sending device to said registering device, three gaseous conductor tubes in said registering device, two of said tubes having their cathodes connected to one of said conductors and their anodes connected to the other of said conductors and each having a different breakdown potential whereby one tube will break down when light negative potential is applied over said one conductor to the cathode thereof and ground is applied over the other said conductor to the anode thereof and whereby both tubes will break down when said negative potential is of increased value, said third tube having its anode connected to said one of said conductors and its cathode connected to said other of said conductors and having a breakdown potential such that when negative potential is applied to the cathode thereof and'ground is applied to the anode thereof said tube breaks down, a relay in the cathode-anode circuit of each tube, registers selectively operable by said relays, and means controlled by said sending device for selectively operating said relays by applying either to said registering device, three gaseous conductor tubes in said registering device, two of said tubes having their cathodes connected to one of said conductors and their anodes connected to the other of said conductors and each having a definite breakdown potential whereby one tube will break down when light negative potential is applied over said one conductor to the cathode thereof and ground is applied over the other of said conductors to the anode thereof and whereby both tubes will break down when said negative potential is of increased value, said third tube having its anode connected to said one of said conductors and its cathode connected to said other of said conductors and having a breakdown potential such that when negative potential is applied to the cathode thereof and ground is applied to the anode thereof said tube breaks down, a relay in the cathode-anode circuit of each tube, registers selectively operable by said relays, means in said register circuit for reversing the connection of said control conductors to said tubes whereby said first two tubes become responsive to the connection of negative potential of increased value to the cathodes thereof over said other of said conductors and ground to the anodes thereof over said one of said conductors, and means controlled by said sending device for selectively operating said relays by applying either light or heavy negative potential to said one of said conductors and ground to said other of said conductors or vice versa.

OSCAR MYERS. 

